All incoming flights were ordered to go into a "holding pattern" - circling outside the designated zone - while three passenger planes diverted to Shannon Airport on the west coast to refuel.

They included two Dublin-bound Aer Lingus services, one from London Gatwick, with 146 travellers onboard, and a flight from Brussels, which had 137 people onboard. A Ryanair flight from Las Palmas also diverted to Shannon. After refuelling they returned to Dublin, about an hour and a half behind schedule.

Another three Aer Lingus passenger flights - from Heathrow, Paris and Dusseldorf - were forced to remain in the skies for a further 20 minutes before they could safely attempt landing.

A Dublin Airport spokesman said the Garda had requested helicopter priority from air traffic control to allow them to follow the armed raiders. "Ordinarily this wouldn't be an issue but it just happened to be in the exact location of the incoming flight path," he said.

The airborne Garda mission followed the hold-up of a cash-in-transit van at the Clare Hall shopping centre, about five miles from the capital's main airport, at around 10:30am.

Investigating officers said one man - believed to be armed with a gun - approached and threatened a security worker delivering cash to the mall before fleeing in a waiting car with an undisclosed sum of cash.

Acting on a tip-off about two men acting suspiciously on the nearby N32, which runs between the shopping centre and the airport, officers rushed to the scene. Two men, aged 28 and 29 years, were arrested and are being held under section 30 Offences Against the State Act at Coolock Garda station.

The cash was recovered and a firearm was also discovered close to the scene of the arrests in the city's northside. A burnt out car similar to the one used in the robbery was located a short time later.